Relatively homogeneous leukocyte interferons have been derived from normal or leukemic donors' leukocytes. These interferons are a family of proteins characterized by a potent ability to confer a virus-resistant state in their target cells. In addition, interferon can act to inhibit cell proliferation and modulate immune response. These properties have prompted the clinical use of interferon as a therapeutic agent for the treatment of viral infections and malignancies.
More recently, recombinant DNA technology has been employed to occasion the microbial production of a number of different leukocyte interferons whose amino acid sequences exhibit on the order of 70 percent homology, one relative to another, all as disclosed in the aforementioned U.S. patent applications of Goeddel an Pestka and in the manuscript of David V. Goeddel et al entitled "The Structures of Eight Distinct Cloned Human Leukocyte Interferon cDNAs", a copy of which is attached as Appendix A to the present application and incorporated herein. The manner in which genes encoding amino acid sequences of various leukocyte interferons designated, inter alia, LeIF A,B,C,D,F,G and H, respectively, are obtained from the cell line KG-1 described in Koeffler, H. P. and Golde, D. W. Science 200, 1153-1154 (1978) is disclosed in the aforementioned applications of Goeddel and Pestka. The cell line KG-1 has been deposited with the American type culture collection, ATCC Accession Number CRL 8031. Such genes, appropriately deployed in plasmidic vehicles for bacterial expression, may be employed to transform host bacteria, preferably E. coli K-12 strain 294, American type culture collection accession No. 31446.